Method for laser cutting polycrystalline diamond structures

ABSTRACT

Methods of laser cutting polycrystalline diamond tables and polycrystalline diamond compacts are disclosed. Laser cutting of the polycrystalline diamond table provides an alternative to electrical-discharge machining (“EDM”), grinding with a diamond wheel, or lapping with a diamond wheel. Grinding or lapping with a diamond wheel is relatively slow and expensive, as diamond is used to remove a diamond material. EDM cutting of the polycrystalline diamond table is sometimes impractical or even impossible, particularly when the cobalt or other infiltrant or catalyst concentration within the polycrystalline diamond table is very low (e.g., in the case of a leached polycrystalline diamond table). As such, laser cutting provides a valuable alternative machining method that may be employed in various processes such as laser scribing, laser ablation, and laser lapping.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 13/166,007filed on 22 Jun. 2011, which is incorporated herein, in its entirety, bythis reference.

BACKGROUND

Wear-resistant, polycrystalline diamond compacts (“PDCs”) are utilizedin a variety of mechanical applications. For example, PDCs are used indrilling tools (e.g., cutting elements, gage trimmers, etc.), machiningequipment, bearing apparatuses, wire-drawing machinery, and in othermechanical apparatuses.

PDCs have found particular utility as superabrasive cutting elements inrotary drill bits, such as roller-cone drill bits and fixed-cutter drillbits. A PDC cutting element typically includes a superabrasive diamondlayer commonly known as a diamond table. The diamond table is formed andbonded to a substrate using a high-pressure/high-temperature (“HPHT”)process. The PDC cutting element may be brazed directly into a preformedpocket, socket, or other receptacle formed in a bit body. The substratemay often be brazed or otherwise joined to an attachment member, such asa cylindrical backing. A rotary drill bit typically includes a number ofPDC cutting elements affixed to the bit body. It is also known that astud carrying the PDC may be used as a PDC cutting element when mountedto a bit body of a rotary drill bit by press-fitting, brazing, orotherwise securing the stud into a receptacle formed in the bit body.

Conventional PDCs are normally fabricated by placing a cemented carbidesubstrate into a container or cartridge with a volume of diamondparticles positioned on a surface of the cemented carbide substrate. Anumber of such cartridges may be loaded into an HPHT press. Thesubstrate(s) and volume(s) of diamond particles are then processed underHPHT conditions in the presence of a catalyst material that causes thediamond particles to bond to one another to form a matrix of bondeddiamond grains defining a polycrystalline diamond (“PCD”) table. Thecatalyst material is often a metal-solvent catalyst (e.g., cobalt,nickel, iron, or alloys thereof) that is used for promoting intergrowthof the diamond particles.

In one conventional approach, a constituent of the cemented carbidesubstrate, such as cobalt from a cobalt-cemented tungsten carbidesubstrate, liquefies and sweeps from a region adjacent to the volume ofdiamond particles into interstitial regions between the diamondparticles during the HPHT process. The cobalt acts as a catalyst topromote intergrowth between the diamond particles, which results information of a matrix of bonded diamond grains having diamond-to-diamondbonding therebetween, with interstitial regions between the bondeddiamond grains being occupied by the solvent catalyst. Once the PCDtable is formed, the solvent catalyst may be at least partially removedfrom the PCD table of the PDC by acid leaching.

It is often desirable to machine the PCD table, for example by forming achamfer into the PCD table or to cut the PDC to provide anon-cylindrical shape. Such cutting has typically been accomplished byelectrical-discharge machining, grinding, lapping or combinationsthereof to remove desired portions of the PCD table and substrate.Despite the availability of such methods, manufacturers and users ofPDCs continue to seek improved PDC manufacturing methods.

SUMMARY

Embodiments of the invention relate to methods of laser cutting PCDstructures, such as PCD tables and PDCs. In many of the disclosedembodiments, a PCD table is provided. Such a PCD table may be separatefrom or bonded to a substrate as part of a PDC. In an embodiment of amethod of shaping a PCD, laser energy is applied to an exterior surfaceof the PCD table to remove diamond material adjacent to the exteriorsurface so as to form a generally V-shaped groove into the PCD table.The V-shaped groove may comprise a scribe line or curve along which thePCD table may then be broken. Such laser scribing may be used to form anon-cylindrical PCD table or PDC from a cylindrical PCD table or PDC,for example, by electrical-discharge machining (“EDM”) wire cutting orotherwise cutting (e.g., grinding) through the remainder of the diamondand/or substrate material generally along the scribe line or groove toform a non-cylindrical PCD table having an oval, square, rectangular, orother shaped profile. In another embodiment, the PCD or PDC may bebroken generally along the scribe line. Although it is possible to formnon-cylindrical PCD tables and PDCs through HPHT processes, suchprocesses are more complex and expensive, often requiring additionalsteps to ensure the integrity of the non-cylindrical diamond table orPDC. Of course, in other embodiments, a generally cylindrical PCD tablemay also be formed by such a process (e.g., by removing a peripheraledge of an initial larger PCD table).

In some embodiments, laser energy is applied to an exterior surface of aprovided PCD table in a series of passes of the laser so that thediamond material is removed to a first depth in a first pass and atleast one subsequent pass thereafter removes diamond material adjacentto and at a depth greater than the diamond material removed in theimmediately previous pass of the laser. Such progressive formation ofthe laser cut in the PCD table prevents or minimizes any thermal damageto the PCD table as the depth of material removed in each pass issufficiently low so as to substantially prevent overheating or damage toadjacent diamond material. For example, such progressive cutting canprevent or minimize back conversion of diamond to graphite or amorphouscarbon that may otherwise result where heat from the laser cutting isabsorbed too rapidly into adjacent diamond material. Multiple passes,particularly when separated by rest periods, allow the heat to betterdissipate, resulting in an overall lower temperature rise within thematerial adjacent to that being laser cut. Although such methods mayallow for very high quality while minimizing damage, in alternativeembodiments, the diamond material may be cut to a desired depth in asingle pass or cut.

In another embodiment, laser energy is applied to a peripheral portionof an exterior surface of a provided generally cylindrical PCD table toremove diamond material from the peripheral portion to form a PCD tablehaving a selected geometry. In an embodiment, the provided generallycylindrical PCD table is bonded to a similarly sized and shapedgenerally cylindrical substrate to define a PDC having a selectedgeometry. The portions of the generally cylindrical substrate that areadjacent to the peripheral portion of the PCD table (i.e., that portionthat is removed) may also be removed by any suitable technique (e.g.,laser cutting, grinding, lapping, electrical-discharge machining, orcombinations thereof) to result in a PDC having a selected geometry,such as a non-cylindrical or a generally cylindrical geometry. Forexample, this method may be used to form PCD tables and PDCs havingoval, square, rectangular, or other shaped profile. Of course, thismethod may also be used to form a PCD table or a PDC that is generallycylindrical (e.g., from a larger initial PDC from which the periphery isremoved).

In another embodiment, laser energy is applied to a peripheral portionof an exterior surface of a provided PCD table to laser cut a chamferinto the PCD table. Such laser cutting of the chamfer may be achievedwithout the need for slow and expensive diamond grinding equipment, andprovides all the benefits of chamfering such as improved wear resistanceand particularly resistance to chipping and breakage.

In another embodiment, laser energy may be applied to an exteriorsurface of a provided PCD table to laser lap the exterior workingsurface to a smooth finish. For example, such a process may be employedto remove protruding portions of the exterior surface, resulting inimproved smoothness. In an embodiment, the exterior surface to be laserlapped may be mapped prior to laser lapping so that it is only necessaryto apply the laser energy to topographically “high” portions needing tobe reduced in profile to provide a smoother exterior surface. In oneembodiment, the finished surface may be flat and smooth, while otherembodiments may provide a smoothly curved (e.g., concave or convex)surface.

Of course, in some embodiments, a plurality of the described lasercutting processes may be combined together in laser cutting a providedPCD table or PDC.

Laser cutting may be used to produce non-planar surfaces. For example,applications for such non-planar shapes may include, but are not limitedto, jewelry and tooling, such as shaped dies, shaped punches, roof bits,bearings, and traction devices.

Features from any of the disclosed embodiments may be used incombination with one another, without limitation. In addition, otherfeatures and advantages of the present disclosure will become apparentto those of ordinary skill in the art through consideration of thefollowing detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate several embodiments of the invention, whereinidentical reference numerals refer to identical or similar elements orfeatures in different views or embodiments shown in the drawings.

FIG. 1A is an isometric view of an embodiment of a PDC including a PCDtable attached to a cemented carbide substrate;

FIG. 1B is an isometric view of a PCD table similar to that shown inFIG. 1A, but not attached to a cemented carbide substrate;

FIG. 1C is a partial cross-sectional view of a PDC including a PCD tablewith a leached exterior region;

FIG. 2A is a partial cross-sectional view of a PCD table including alaser cut generally V-shaped groove cut therein;

FIG. 2B is a partial cross-sectional view of a PCD table showing how thelaser cut may be formed progressively wider and progressively deeperwith a plurality of passes of the laser according to an embodiment;

FIG. 2C is a partial cross-sectional view of a PDC in which a laser cuthas been formed through the PCD table portion of the PDC, leaving thesubstrate of the PDC intact, according to an embodiment;

FIG. 2D is a partial cross-sectional view of a PDC including a PCD tablewith a leached exterior region similar to that of FIG. 1C in which alaser cut has been formed through the PCD table portion of the PDC,leaving the substrate of the PDC intact, according to an embodiment;

FIG. 3A is a cross-sectional schematic view of a generally cylindricalPDC in which a peripheral portion of the PCD table of the PDC is to beremoved by laser cutting and adjacent portions of the substrate are alsoto be removed according to an embodiment;

FIG. 3B is top plan view of the cylindrical PDC of FIG. 3A showingperipheral regions to be removed to form an oval PDC;

FIG. 4A is a top plan view of a generally cylindrical PDC and in whichperipheral portions of the PCD table of the PDC are to be removed bylaser cutting according to an embodiment;

FIG. 4B is a cross-sectional view of the PDC of FIG. 4A once theselected peripheral portions of the PCD table are removed by lasercutting;

FIG. 5 is a top plan view of another generally cylindrical PDC showinganother shape for a PDC formed by removing a selected peripheral portionof the cylindrical PDC according to an embodiment;

FIG. 6 is a partial cross-sectional view of a PDC showing a laser cutchamfer formed therein according to an embodiment;

FIG. 6A is a partial cross-sectional close up view of a PDC showing howa laser cut chamfer may be formed according to one embodiment;

FIG. 6B is a partial cross-sectional close up view of a PDC showing howa laser cut chamfer may be formed according to an alternativeembodiment;

FIG. 6C is a partial cross-sectional close up view of a PDC showing alaser cut chamfer that is disposed radially inwardly relative to thelateral surface of the PCD table;

FIG. 7A is a close up cross-sectional view of an exterior surface of aPCD table including an initially rough surface with protrusions that canbe smoothed by laser lapping;

FIG. 7B is a close up cross-sectional view of the exterior surface ofthe PCD table of FIG. 7A after the protrusions have been removed bylaser lapping according to an embodiment;

FIGS. 8A and 8B show before and after cross-section elevation views bywhich an initially non-flat surface may be laser cut to result in a flatsurface;

FIGS. 9A and 9B show before and after cross-section elevation views bywhich a flat surface may be laser cut to result in a non-flat, convexsurface;

FIGS. 10A and 10B show before and after cross-section elevation views bywhich a flat surface may be laser cut to result in a non-flat, concavesurface;

FIGS. 11A-11C show before and after cross-section elevation views and atop view (after) by which a flat surface may be laser cut to include alower step portion and an upper step portion;

FIGS. 12A and 12B show a top plan view and an elevation view,respectively, of a laser cut surface that may include multiple recessesor pockets;

FIGS. 13A and 13B show a top plan view and an elevation view,respectively, of a laser cut surface that may include multipleprotrusions;

FIGS. 14A and 14B show a top plan view and a cross-sectional view,respectively, of a laser cut surface including multiple facets;

FIGS. 15A-15C show cross-sectional views of additional shaping that maybe achieved along the outside diameter of the PCD table through lasercutting according to various embodiments;

FIG. 16 is an isometric view of an embodiment of a rotary drill bit thatmay employ one or more of PDCs manufactured according to the any of thedisclosed embodiments; and

FIG. 17 is a top elevation view of the rotary drill bit shown in FIG.16.

DETAILED DESCRIPTION I. Introduction

Embodiments of the invention relate to methods of laser cutting PCDstructures, such as PCD tables and PDCs. Laser cutting of the PCD tablesand PDCs provides an alternative to EDM, grinding with a diamond wheel,or lapping with a loose abrasive, such as diamond (e.g., loose drydiamond, wet diamond, or slurry diamond). Grinding or lapping with adiamond wheel is relatively slow and expensive, as diamond is used toremove a diamond material. EDM of the PCD table is sometimes impracticalor even impossible, particularly when the amount of cobalt or otherelectrically conductive infiltrant or catalyst within the PCD table isvery low (e.g., in the case of a leached PCD table). As such, lasercutting provides a valuable alternative machining method that can beemployed in various processes.

As used herein, the term “laser cutting” or variants thereof encompasseslaser ablation, laser scribing, and laser lapping. In addition, “laserscribing” and variants thereof is a subset of laser ablation.

As used herein, the term “laser ablation” or variants thereof refers toa process in which laser energy is applied to a given surface (e.g., ofa diamond material) to evaporate or vaporize a kerf into the surface.The kerf may extend partially or fully through a thickness of thediamond material.

As used herein, the term “laser scribing” or variants thereof refers toa process in which laser energy is applied to a given surface (e.g., ofa diamond material) to ablate a kerf partially through the surface,leaving a connecting portion uncut. The structure may then be brokenalong the laser scribed scribe line or curve.

As used herein, the term “laser lapping” or variants thereof refers to aprocess in which laser energy is applied to protrusions extending from agiven surface (e.g., of a diamond material) to evaporate or vaporize theprotruding portions, resulting in a surface with greater smoothness thanprior to laser lapping.

II. Polycrystalline Diamond Tables and Compacts

FIG. 1A is an isometric view of an embodiment of a PDC 100 including aPCD table 102 attached to a cemented carbide substrate 108 along aninterfacial surface 105 thereof. FIG. 1B shows a PCD table 102 that mayotherwise be similar to table 102 of FIG. 1A, but which is unattached toany substrate. In either case, the PCD table 102 includes a plurality ofdirectly bonded-together diamond grains exhibiting diamond-to-diamondbonding (e.g., sp³ bonding) therebetween. The PCD table 102 includes atleast one lateral surface 104, an upper exterior working surface 106,and an optional chamfer 107 extending therebetween. It is noted that atleast a portion of the at least one lateral surface 104 and/or thechamfer 107 may also function as a working surface that contacts asubterranean formation during drilling operations.

The bonded together diamond grains of the PCD table 102 may exhibit anaverage grain size of about 100 μm or less, about 40 μm or less, such asabout 30 μm or less, about 25 μm or less, or about 20 μm or less. Forexample, the average grain size of the diamond grains may be about 10 μmto about 18 μm, about 8 μm to about 15 μm, about 9 μm to about 12 μm, orabout 15 μm to about 25 μm. In some embodiments, the average grain sizeof the diamond grains may be about 10 μm or less, such as about 2 μm toabout 5 μm or submicron.

The diamond particle size distribution of the diamond particle mayexhibit a single mode, or may be a bimodal or greater grain sizedistribution. In an embodiment, the diamond particles of the one or morelayers of diamond particles may comprise a relatively larger size and atleast one relatively smaller size. As used herein, the phrases“relatively larger” and “relatively smaller” refer to particle sizes (byany suitable method) that differ by at least a factor of two (e.g., 30μm and 15 μm). According to various embodiments, the diamond particlesmay include a portion exhibiting a relatively larger average particlesize (e.g., 50 μm, 40 μm, 30 μm, 20 μm, 15 μm, 12 μm, 10 μm, 8 μm) andanother portion exhibiting at least one relatively smaller averageparticle size (e.g., 6 μm, 5 μm, 4 μm, 3 μm, 2 μm, 1 μm, 0.5 μm, lessthan 0.5 μm, 0.1 μm, less than 0.1 μm). In an embodiment, the diamondparticles may include a portion exhibiting a relatively larger averageparticle size between about 10 μm and about 40 μm and another portionexhibiting a relatively smaller average particle size between about 1 μmand 4 μm. In some embodiments, the diamond particles may comprise threeor more different average particle sizes (e.g., one relatively largeraverage particle size and two or more relatively smaller averageparticle sizes), without limitation.

It is noted that the as-sintered diamond grain size may differ from theaverage particle size of the diamond particles prior to sintering due toa variety of different reasons, such as grain growth, diamond particlesfracturing, carbon provided from another carbon source (e.g., dissolvedcarbon in the metal-solvent catalyst), or combinations of the foregoing.

The PCD table 102 may exhibit a thickness “t” of at least about 0.040inch, such as about 0.045 inch to about 1 inch, about 0.045 inch toabout 0.500 inch, about 0.050 inch to about 0.200 inch, about 0.065 inchto about 0.100 inch, or about 0.070 inch to about 0.100 inch (e.g.,about 0.09 inch). The PCD table 102 may or may not include a catalyst orinfiltrant disposed in at least a portion of the interstitial regionsbetween the bonded diamond grains of the PCD table 102. The infiltrantmay include, but is not limited to, iron, nickel, cobalt, and alloys ofthe foregoing metals. For example, the infiltrant may be provided fromthe substrate 108 (e.g., cobalt from a cobalt-cemented carbidesubstrate). In embodiments in which a region of the PCD table 102includes substantially no catalyst or infiltrant (e.g., less than about2% by weight, or no more than about 1% by weight), the catalyst orinfiltrant may have been removed by leaching, for example, by immersingthe PCD table 102 in an acid, such as aqua regia, nitric acid,hydrofluoric acid, mixtures thereof, or other suitable acid. Forexample, leaching the PCD table 102 may form a leached region thatextends inwardly from the exterior surface 106, the lateral surface 104,and the chamfer 107 to a selected leached depth. The selected leacheddepth may be about 100 μm to about 1000 μm, about 100 μm to about 300μm, about 300 μm to about 425 μm, about 350 μm to about 400 μm, about350 μm to about 375 μm, about 375 μm to about 400 μm, about 500 μm toabout 650 μm, or about 650 μm to about 800 μm.

Valuable metals (e.g., cobalt, nickel, etc.) may be recovered followingacid leaching by carbon monoxide extraction, for example, as disclosedin U.S. Pat. No. 4,322,390, herein incorporated by reference.

FIG. 1C shows a cross-sectional view through an exemplary PCD table 102′which has been leached to include a leached region 103 adjacent toexterior surface 106 and extending inwardly therefrom to region 101,within which the concentration of catalyst or infiltrant has not beensignificantly reduced as a result of leaching. It will be understoodthat use of a laser for removal of material of the diamond table (orunderlying substrate 108) may be carried out on leached or un-leachedPCD diamond tables. The ability to laser cut a leached diamond table,which may include no or a very low concentration of electricallyconductive catalyst or infiltrant material is particularly advantageous.For example, EDM cutting of leached diamond table structures can provedifficult and can sometimes be a practical impossibility because ofinsufficient electrical conductivity within the diamond table to be cut.Laser cutting offers an alternative that does not require a minimumthreshold level of electrical conductivity within the part in order toallow cutting of the part.

U.S. Pat. No. 7,866,418, herein incorporated by reference, discloses PCDtables and associated PCD compacts formed under conditions in whichenhanced diamond-to-diamond bonding occurs. Such enhanceddiamond-to-diamond bonding is believed to occur as a result of thesintering pressure (e.g., at least about 7.5 GPa) employed during theHPHT process being further into the diamond stable region, away from thegraphite-diamond equilibrium line. The PCD tables and compacts disclosedtherein, as well as methods of fabrication are suitable for lasercutting according to the methods disclosed herein. Generally, as thesintering pressure is increased above 7.5 GPa, a wear resistance of thePCD so-formed may increase. For example, the G_(ratio) may be at leastabout 4.0×10⁶, such as about 5.0×10⁶ to about 15.0.×10⁶ or, moreparticularly, about 8.0×10⁶ to about 15.0×10⁶. In some embodiments, theG_(ratio) may be at least about 30.0×10⁶. The G_(ratio) is the ratio ofthe volume of workpiece cut to the volume of PCD worn away during thecutting process. An example of suitable parameters that may be used todetermine a G_(ratio) of the PCD are a depth of cut for the PCD cuttingelement of about 0.254 mm, a back rake angle for the PCD cutting elementof about 20 degrees, an in-feed for the PCD cutting element of about6.35 mm/rev, a rotary speed of the workpiece to be cut of about 101 RPM,and the workpiece may be made from Barre granite having a 914 mm outerdiameter and a 254 mm inner diameter. During the G_(ratio) test, theworkpiece is cooled with a coolant, such as water.

The substrate 108 may comprise a plurality of tungsten carbide or othercarbide grains (e.g., tantalum carbide, vanadium carbide, niobiumcarbide, chromium carbide, and/or titanium carbide) cemented togetherwith a metallic cementing constituent, such as cobalt, iron, nickel, oralloys thereof. For example, in an embodiment, the cemented carbidesubstrate is a cobalt-cemented tungsten carbide substrate. In someembodiments, the substrate 108 may include two or more differentcarbides (e.g., tungsten carbide and chromium carbide).

The PCD table 102 may be formed separately from or integral with thesubstrate 108 in an HPHT process. When formed separately, the PCD table102 may be subsequently attached to the substrate 108 in another HPHTprocess. The temperature of such HPHT process may typically be at leastabout 1000° C. (e.g., about 1200° C. to about 1600° C.) and the pressureof the HPHT process may typically be at least about 4.0 GPa (e.g., about5.0 GPa to about 12.0 GPa, about 7.0 GPa to about 9.0 GPa, about 6.0 GPato about 8.0 GPa, or about 9.0 GPa to about 12.0 GPa).

III. Laser Cutting Methods

FIG. 2A shows the PCD table 102 includes a groove 110 (e.g., generallyV-shaped) that has been cut with a laser according to an embodiment. PCDtable 102 may comprise a leached portion of a PCD diamond table asdescribed in conjunction with FIG. 1C. As shown, the groove 110 mayextend only partially through PCD table 102 to form a scribe line alongwhich the PCD table 102 may be broken. In an embodiment, rather thancutting the full depth of the groove 110 in a single trajectory, themethod employs multiple passes to cut progressively deeper with eachpass until the laser cuts to the desired depth, or entirely through thestructure. In an embodiment, the majority (e.g., substantially all) ofany slag resulting from the laser cutting is also removed by the laser(e.g., by ablation) from the side walls 112 and 114 of the groove 110 asthe groove 110 is progressively deepened. Slag removal is one benefit offorming groove 110 with multiple passes rather than a single cut.

As shown in FIG. 2A, the laser may be used to cut tapered sidewalls 112and 114 so as to form a groove 110. In an embodiment, the PCD table 102is subsequently broken along groove 110. For example, breaking of thePCD table 102 may occur along line 118 that emanates generally fromlowermost region 116 (e.g., a vertex or cusp) of the groove 110.Formation of the groove 110 is advantageous as the laser-cut groove orscribe line 110 may terminate in a substantial point as viewed intransverse cross-section (or a line as viewed in plan view), providing afracture point or line along which the PCD table 102 may be broken.

Scribing and breaking of a PCD table or PDC may be useful for fracturetoughness testing and/or cross-sectional analysis. Scribing and breakingcould also be used in forming a smaller PCD table or PDC (e.g.,non-cylindrical in shape), although preferably excess portions would becut or ground away (e.g., through laser cutting, EDM, or grinding) asdescribed in greater detail below in conjunction with FIGS. 3A-5 inorder to produce a smaller (and perhaps non-cylindrical in shape) PCDtable or PDC.

The V-shaped groove 110 is wider at its top, adjacent exterior topsurface 106, and narrows towards lower most region 116. In generalterms, V-shaped grooves may include various other shapes that do notterminate in a vertex as shown. For example, the groove mayalternatively be U-shaped, including a radius of curvature adjacentlower most region 116. Alternatively, the groove 110 may beflat-bottomed as shown in FIG. 2C. Such alternatives, as well as othersthat will be apparent to one of skill in the art, are encompassed withinthe term groove as used herein.

Fracture point or line 118 emanating from region 116 may be mostadvantageous as compared to a other groove shapes (e.g. a laser cut thatdoes not terminate in a vertex), as it would be difficult to guidefracture of the PCD table 102 along a desired fracture line. Forexample, if the sidewalls 112 and 114 were not tapered so as toterminate in the vertex 116, but were substantially parallel to oneanother so that the “bottom” of the laser cut included a floor with somewidth defined between the sidewalls 112 and 114, fracture of the floorcould occur at any point along the floor between sidewalls 112 and 114.

Providing a vertex so that the “bottom” of the cut terminates in a pointwith substantially zero width rather than a floor having some givenwidth forces fracture to occur along the line 118. The particular anglesof the sidewalls 112 and 114 may depend on the particular power andfocus characteristics selected during operation of the laser. Forexample, higher power produces less taper, and greater focus of thelaser will also produce less taper. Similarly, lower power producesgreater taper, while lower or “softer” focus also produces greatertaper.

In another embodiment, the method is directed to a method ofprogressively cutting into or through the PCD table 102 in multiplepasses of the laser. Such a method of progressively deeper cutting maybe performed in conjunction with cutting of a V-shaped groove asdescribed above and shown in FIG. 2A, or alternatively such lasercutting may form another shaped laser cut (e.g., one bounded bysubstantially parallel sidewalls, or one bounded by outwardly taperedsidewalls rather than inwardly tapered sidewalls as shown in FIG. 2A.

FIG. 2B schematically illustrates how a V-shaped groove similar to thatshown in FIG. 2A may be formed by multiple passes of the laser to cutprogressively wider and progressively deeper into the PCD table 102according to an embodiment. The groove 110 may be formed progressivelythrough multiple stages (e.g., a first stage 120 having a greatestwidth, a second stage 122 having an intermediate width, a third stage124 having an intermediate width narrower than stage 122, and a fourthstage 126 having a narrowest width. For example, the first stage 120 maybe formed by applying laser energy in one or more first stage passes tothe exterior surface 106 of the PCD table 102 to ablate diamond materialadjacent to the exterior surface 106 and within the first stage 120.

When forming the V-shaped groove 110, the first stage 120 will have thegreatest width. The taper of the sidewalls may be achieved by selectingappropriate power and focus settings of the laser when cutting kerfsadjacent to sidewalls 112 and 114. Lower power, a less (e.g., softer)focused, more diffuse beam of laser energy, or combinations thereof maybe used to increase the angle of the taper. Depending on the desireddepth of the final cut groove 110, and the characteristics of theparticular laser employed, more than one pass of the laser may berequired to complete cutting of the first stage 120. For example, if thekerf width provided by the laser is of a width as shown by hash marks128, four passes of the laser would be required to ablate diamondmaterial to a depth represented by the first stage 120. Once the diamondmaterial within the first stage 120 has been ablated, cutting may beginon the second stage 122, which requires fewer passes of the laser (e.g.,3 kerf widths wide), as the sidewalls 112, 114 are tapered. Similarly,once the diamond material from the second stage 122 has been ablated,cutting may begin on third stage 124, which requires fewer passes of thelaser as compared to the previous stage (e.g., 2 kerf widths wide). Thefinal stage may be only a single kerf width wide, and may terminate in asubstantial vertex, if desired.

Employing multiple passes of the laser to form groove 110 is helpful inavoiding thermally induced damage to the PCD material of region 102, aswell as when laser cutting through substrate 108. The inventor hasobserved that thermally induced damage may be more likely to occur whenlaser cutting the substrate 108 than PCD region 102. As such, the widthand depth associated with cutting in substrate 108 may be smaller thanwhen cutting within PCD material 102 so as to minimize or prevent anythermal damage to the PCD table 102 or substrate 108.

In some embodiments, the groove 110 is not to be used as a scribe linealong which the PCD table 102 is broken, and the groove or cut 110 maynot terminate in a substantial vertex, but may exhibit a “floor” 116′having a given width between sidewalls 112 and 114 (e.g., as seen inFIG. 2C). In one embodiment, a laser-cut groove 110 may be formed on oneside of the PCD table or PDC, while an aligned cut may be formed on theopposite “bottom” side (e.g., by laser cutting or EDM) to complete thecut. Such an embodiment may be particularly helpful for laser cuttingthrough a low conductivity (e.g., leached) diamond PCD table, while EDMmay be used to cut through the opposite surface. The opposite surfacemay be tungsten carbide substrate and/or higher conductivity(substantially un-leached) diamond.

The angles of the sidewalls 112 and 114 are determined, at least inpart, based on the power, focus, and other beam quality characteristicsselected during operation of the laser. It may be advantageous torefocus the laser periodically, for example after between about 0.001inch and about 0.15 inch (e.g., about 0.001 inch and about 0.01 inch) ofdiamond material has been ablated or removed from the cut. In anembodiment, refocusing may occur between about 0.003 inch to about 0.05inch (e.g., about 0.003 inch to about 0.007 inch) of diamond materialremoved from the cut. In another embodiment, refocusing may occurbetween about 0.004 inch and about 0.006 inch (e.g., about 0.005 inch)of diamond material removed from the cut. In one embodiment, one stagemay be as deep as about 0.15 inch, depending on the power of the laserand the diamond material being cut. In addition, the power and focuscharacteristics employed when cutting adjacent to the sidewalls 112 and114 may differ from the power and focus settings when cutting kerfswithin the central portion of the cut.

The number of stages associated with any particular cut may depend onthe total depth desired. For example, where the total depth isrelatively shallower, relatively fewer stages may be required, and wherethe total depth is deeper, more stages may be required. For example,where a total depth of cut is intended to be only about 0.003 inch(e.g., a shallow scribe line), perhaps only one stage may be required.Where a total depth of about 0.1 inch is desired, many more stages maybe required, and it may be advantageous to provide a rest period betweencuts so as to allow heat to better dissipate from the PCD table 102.Where rest periods are provided, the period of rest may be between about0.2 times and about 3 times that of the active cut time, more preferablybetween about 0.5 times and about 2 times that of the active cut time,and even more preferably about equal to the active cut time.

Laser cuts of any desired depth may be formed according to the disclosedembodiments of methods. Often, the depth of cut desired may depend onthe purpose for the cut. Where the cut is formed as a scribe line asshown in FIG. 2A along which the PCD table 102 may be broken, a depth ofas little as about 0.003 inch may be sufficient, particularly where thePCD table 102 may have a total thickness between about 0.04 inch andabout 0.1 inch. Where the purpose of the cut is to entirely remove aperipheral portion of the PCD table 102 of a PDC, significantly greaterdepth, up to the full thickness of the PCD table (e.g., about 0.1 inch)may be desired.

FIG. 2C shows the PCD table 102 attached to the substrate 108 in which alaser cut portion 110′ has been formed through the PCD table 102,leaving the substrate 108 substantially intact, according to anembodiment. Of course, it may be possible to cut through the carbidesubstrate 108 with the laser, although alternative cutting methods forcutting the carbide substrate are also contemplated by the presentdisclosure. PCD products can be processed from an as-pressed conditionas provided from the HPHT process to a finished diameter or dimensionsmuch more efficiently and with substantially lower cost by firstremoving desired portions of the PCD table with laser ablation and/orlaser scribing. These processes may be followed by final grinding, whererelatively small residual portions of the diamond material may requireremoval, although the vast majority of diamond material to be removed isremoved through laser cutting, leaving relatively little, if any, to beremoved by a grinding or EDM process.

For example, the portion 110′ of the PCD table 102 may be removed bylaser cutting. The portion 110′ is bounded by sidewalls 112′ and 114′ aswell as a floor 116′ having a width defined between sidewalls 112′ and114′. Attempting to remove the portion 110′ by EDM includes attendantrisks, as interaction of EDM and residual stresses within the PCD table102 can result in cracking in the PCD table 102 and/or the substrate108. To minimize or eliminate this problem, a laser trough/groove orportion 110′ may be formed (e.g., with multiple passes of the laser toachieve both the desired width and depth) in the PCD table 102, or eventhe substrate 108. Gradual removal of the diamond material from the top,exterior surface 106 (or alternatively from another exterior surfacesuch as the side or the bottom of a PCD table that is unattached to asubstrate) of the PCD table 102 has been found to relieve stress in thepart more uniformly. As such, laser cutting can reduce the risk ofbreakage as compared to EDM machining.

For example, when the PCD table 102 is cut with EDM, and the EDM wire isnormal to the exterior surface 106, a stress gradient is formed at theleading edge of the cut. EDM through the PCD table 102 is believed toconcentrate the stress at the leading edge of the cut, which may resultin cracking of the diamond table and/or substrate.

Thus, once the portion 110′ has been formed through the PCD table 102 bylaser cutting, the stresses are at least partially relieved, and EDM maybe more reliably used for cutting through the substrate 108.

FIG. 2D illustrates laser cutting of a groove 110 into a PCD table 102′that specifically includes a leached region or layer 103 and an adjacentsubstantially un-leached region of layer 101 between leached layer andsubstrate 108. Groove 110 is formed through leached region 103, and mayextend into substantially un-leached region 101. Although not shown,groove 110 may also extend through un-leached region 101 and intosubstrate 108. As a practical matter, such a groove formed into leachedregion 103 may be difficult or impossible to form by wire EDM, as theleached region 103 exhibits insufficient electrical conductivity to becut by EDM. Thus, laser cutting provides a distinct advantage, as itallows cutting of such diamond table surfaces that exhibit relativelylow electrical conductivity. Further cutting through substrate 108 maybe achieved by EDM or laser cutting, as desired.

Laser cutting into electrically low conductivity region 103 andoptionally into higher conductivity region 101 is also believed toreduce stresses within regions 103 and 101, reducing risk of crackingduring any subsequent EDM operation. Such a laser cut may be shaped asshown in FIG. 2C to include a “floor” and be made wide enough toaccommodate an EDM wire. The desired width and depth may be achievedthrough multiple passes of the laser.

FIG. 3A illustrates a method of laser cutting a PDC according to anotherembodiment. As shown in FIG. 3A, a generally cylindrical PDC 100 (e.g.,such as that shown in FIG. 1A) is provided, and laser energy is appliedto a peripheral portion 130 of the PCD table 102 to ablate diamondmaterial within the peripheral portion 130. Corresponding peripheralportions 132 of the substrate 108 may also be removed (as described ingreater detail below) so as to result in a PDC of a different shape thaninitial PDC 100. Removal of peripheral portions 132 may be through lasercutting, or by other suitable methods (e.g., EDM, CG, etc.). Forexample, a PDC formed according to such a method may be non-cylindricalin profile (e.g., square, rectangular, oval, etc. in profile) orgenerally cylindrical in profile, as desired.

As shown in FIG. 3B, the top plan view and cross-section of the finishedPDC 150 may be oval in profile and cross-section once peripheralportions 130 of PDC 100 and corresponding portions of substrate 108 areremoved. Non-standard, irregular shapes may also be possible. Forexample, FIGS. 4A and 4B show a top plan view and a cross-sectional sideview, respectively of a PDC 150′ that is generally pie shaped in topview profile and cross-section according to another embodiment. PDC 150′is bounded by a curved edge 152 defined by the radius of a portion ofPDC 100 and also straight edges 154′ and 156′. The shape illustrated inFIG. 4A results once peripheral portion 130′ of the PCD table of PDC 100is removed by laser cutting and corresponding portions of the underlyingsubstrate (shown in FIG. 4B as 132′) are also removed. FIG. 4B shows across-sectional view in an intermediate state once the peripheralportion 130′ has been removed, but the corresponding peripheral portion132′ of substrate 108 has not yet been removed.

FIG. 5 shows a top plan view of another embodiment of an irregular shapePDC 150″ that may be formed from a generally cylindrical PDC 100 bylaser cutting away PDC table peripheral portion 130″ and also removingthe corresponding peripheral portion of the substrate 108 underlyingperipheral portion 130″ of the PCD table. Although the illustratedshapes show removal of a peripheral portion of the diamond table, itwill be understood that in another embodiment, it may be possible toremove a centrally disposed portion, rather than just a peripheralportion (e.g., so as to result in a donut shaped PDC).

Removal of the underlying peripheral portion of the substrate 108 thatcorresponds to the laser removed portion of the PCD table 102 may beaccomplished by any desired technique. For example, it may also beremoved by laser cutting, or it may alternatively and/or additionally beremoved by EDM, grinding, lapping, combinations thereof, or anothersuitable technique. Where removal may be by EDM and the removal requiresthe EDM wire to have a pathway from the exterior edge to an interiorcutting path, the laser may be used to laser cut a pathway from theexterior edge of the part to the interior path. Although the substrate108 may comprise a very hard material (e.g., tungsten carbide), it issignificantly less hard than the PCD table 102, so that removal bymechanical techniques are much faster and less expensive than use ofmechanical techniques to remove diamond material. Exemplary CNC grindingtechniques are disclosed in U.S. patent application Ser. No. 12/558,939filed Sep. 14, 2009, which is incorporated herein by reference in itsentirety.

Although the above description generally describes laser cutting of“top” exterior surface 106 of PCD table 102, it will be understood thatlaser cutting may also be performed on peripheral surface 104 of PCDtable 102 (e.g., cutting grooves into the side of table 102), or intoperipheral surface or bottom substrate of 108.

FIG. 6 illustrates a PDC 100 in which laser energy has been applied to aperipheral portion of PCD table 102 extending between exterior “top”working surface 106 and lateral “side” surface 104 so as to remove atriangular region 109 seen in the cross-sectional view of FIG. 6,resulting in a laser-cut chamfer surface 107, according to anembodiment. The laser energy applied to form chamber surface 107 may beapplied from a direction that is radially inward relative to peripheraledge 104, above top exterior surface 106. Alternatively, the laserenergy may be applied from a direction that is radially outward relativeto peripheral edge, where the laser source is positioned below surface106. In addition, a chamfer may be formed within table 102 that is notadjacent to peripheral edge 104, but is located radially inwardly fromperipheral edge 104 (e.g., similar to groove 110′ of FIG. 2C).

The laser-cut chamfer 107 may prevent or minimize any tendency for thesurface 106 and/or 104 to chip or break at their intersection, as aresult of the shallower angle formed therebetween. Formation of thechamfer 107 by laser cutting, rather than by grinding or by EDM isadvantageous, as EDM can result in stress fractures within the PCD table102 as described above, and grinding the PCD table 102 with a diamondwheel in order to form a chamfer is slow and expensive, because diamondis being used to grind away diamond, and no harder material for thediamond wheel is known. Thus, methods of laser cutting the chamfer 107may be less expensive, may be achieved more quickly, and may result inless waste (i.e., as product is damaged during EDM chamfering). Thechamfer 107 may be smooth or have another shape formed by laser cutting,such as being serrated.

In any of the above described laser cutting techniques, the entireportion of the PCD table 102 removed to form the chamfer 107 may beablated away by the laser. FIG. 6A illustrates such an embodiment. Forexample, when laser cutting a chamfer into the PCD table 102, the kerfof the one or more passes of the laser L may entirely ablate thetriangular region 109. In another embodiment, a portion 109 a of the PCDtable may be ablated within the kerf of the laser L, while an adjacentportion 109 b may simply become disconnected from the remainder of thePCD table 102. FIG. 6B shows such an alternative embodiment in which thekerf may simply cut through PCD table 102 at 109 a along chamfer surface107, leaving an un-ablated portion (triangular region 109 b) that may bediscarded or recycled.

In either embodiment, the chamfer may be formed on a surface of the PCDtable 102 that is disposed radially inwardly relative to originallateral surface 104. For example, as shown in FIG. 6C, Groove 110 may belaser cut into PCD table 102, after which a chamfer 107 may be formedaccording to either of the techniques discussed above in conjunctionwith FIG. 6A or 6B. The peripheral portion of table 102 between originallateral surface 104 and groove 110 may be removed by any suitable method(e.g., laser cutting, EDM, grinding, breaking, etc.). In one embodiment,such a peripheral portion of table 102 may be removed by laser cutting(e.g., ablated) by rotating the PCD table or PDC while applying laserenergy to the peripheral surface 104. Such a technique may employmultiple rotations of the PCD table or PDC, and the laser may be appliedgenerally perpendicular to the rotational axis of the PCD table or PDC.The laser may also be moved longitudinally “up” and/or “down” parallelto the axis of rotation (e.g., the axis of rotation may be thelongitudinal axis of the PCD table or PDC).

FIGS. 7A and 7B illustrate how laser cutting may be employed in lappingthe exterior surface 106 of the PCD table 102 according to anembodiment. When the PCD table 102 is formed through an HPHT process,the exterior surface 106 may not be perfectly smooth, flat, or of thedesired shape. For example, where a flat, smooth surface is desired theinitial exterior surface 106 may include one or more protrusions 134extending from and/or recesses 136 within the exterior surface 106.Polishing or lapping of the surface may sometimes be achieved by lappingthe exterior surface 106 against another diamond exterior surface, e.g.,by grinding or lapping. In addition to being relatively slow andexpensive, such techniques include an attendant risk that one or moregrains of diamond material may be pulled from exterior surface 106,destroying the part or at least requiring further grinding and/orpolishing.

In an embodiment, laser cutting may be used to selectively removeprotrusions such as protrusions 134 by applying laser energy to theprotrusions 134 of the exterior surface 106 so as to remove (e.g.,ablate) the diamond material of such protrusions. If any recesses (e.g.,recess 136) are present, these may be removed by further lapping theentire exterior surface so as to bring it at least “down” to the bottomof the recess, as shown in FIG. 7B. This final leveling so as to removeany recesses may be accomplished by laser cutting away a depth of theentire exterior surface 106 (optionally including recess 136, e.g., upto or beyond recess 136) or by grinding or lapping against anotherdiamond surface. Where grinding or lapping is employed, the risk ofinadvertent removal of one or more grains of diamond material isreduced, as any protrusions 134 were previously removed by lasercutting. Laser removal of protrusions 134 further reduces the risk ofpropagation of micro-cracks within the diamond material.

In an embodiment, the laser cutting may apply laser energy across theexterior surface, so as to ablate any protrusions extending therefrom.In another embodiment, the exterior surface 106 may first be mapped(e.g., electronically, photographically, or by laser mapping) toidentify the locations of the protrusions 134 (as well as any recesses136), and then the protrusions 134 may be specifically targeted forremoval by applied laser energy. In other words, the laser energy maynot be applied over the entire exterior surface, but simply to thosespecific protruding areas 134 requiring removal. However, in someembodiments, laser cutting may be used to apply energy across the entireplanarized surface 106′. For example, the substantially planarizedexterior surface 106′ may be formed via laser cutting to provide adesired PCD table thickness. As shown in FIG. 7B, a final substantiallyplanarized exterior surface 106′ (e.g., up to or beyond the recess 136shown in FIG. 7A) formed as a result of the lasing process is smootherthan the initial exterior surface 106.

In the embodiments discussed above for laser chamfering and laserplanarizing, the PCD table may be freestanding (i.e., not attached to asubstrate in substantially fully leached or un-leached form) or attachedto the substrate (i.e., a PDC such as the PDC 100). For example, afreestanding PCD table may be laser chamfered, leached to at leastpartially remove a catalyst used in the formation thereof, and attachedto a substrate 108 in a subsequent HPHT process and/or brazing process.

For some applications, the exterior surface 106 or 106′ may benon-planar (e.g., jewelry or tooling such as punches, dies, roof bits,mining tools, road material removal tools, and/or traction devices).Such non-planar surfaces can be formed by the laser cutting methodsdisclosed herein. For example, laser cutting of the surface can even beused to form three-dimensional sculptures (e.g., of people or anyobject) for jewelry or other aesthetic products.

Laser cutting is not limited to removal of topographical protrusions,but may be used to achieve any of various desired shapes (e.g.,non-planar shapes). For example, as shown in FIGS. 8A and 8B, aninitially non-flat surface 106 may be laser cut to result in a flatsurface 106′, a flat surface 106 (FIG. 9A) may be laser cut to result ina non-flat, convex surface 106′ (FIG. 9B), or a flat surface 106 (FIG.10A) may be laser cut to result in a non-flat, concave surface 106′(FIG. 10B). Such concave or convex surfaces may be useful for convex orconcave bearings. FIGS. 11A-11C show laser cutting of an initially flatsurface 106 so as to include a lower step portion 106 a′ and an upperstep portion 106 b′. Other geometries may be formed in furtherembodiments. For example, the initial surface may be convex or concaveand then be laser formed to a final convex or concave shape.

FIGS. 12A and 12B show a top plan view and an elevation view,respectively, of a finished surface 106′ that may include multiplerecesses or pockets 136. FIGS. 13A-13B show a top plan view and anelevation view, respectively of a finished surface 106′ that may includemultiple protrusions 134 that may be of any shape.

FIGS. 14A and 14B show a top plan view and a cross-sectional view,respectively, of a shaped surface 106′ that may be laser cut to includemultiple facets 106 a′-106 e′. Such shapes may be useful in PDC anvils,gem cut PCD, polycrystalline boron nitride, silicon carbide, etc.According to another embodiment, such laser cutting may be employed tolaser cut a PCD table or PDC to a desired PCD table thickness (e.g., byremoving some of the PCD table to achieve a desired thickness).

FIGS. 15A-15C show cross-sectional views of additional shaping that maybe achieved along the outside diameter of the diamond table throughlaser cutting according to various embodiments. For example, FIG. 15Ashows a cross-sectional view of a PDC including a PCD table 102 in whichthe peripheral edge 104 has been laser cut to include a serrated toothpattern. FIG. 15B shows a cross-sectional view of a PDC including a PCDtable 102 in which the peripheral edge 104 has been laser cut to includea radius chamfer 107′. FIG. 15C shows a cross-sectional view of a PDCincluding a PCD table 102 in which the peripheral edge 104 has beenlaser cut to include a curved, radiused recess formed into theperipheral edge 104. In some embodiments, the PCD table 102 exhibit twoor more of a serrated tooth pattern (FIG. 15A), a radius chamfer (FIG.15B), or a curved radiused recess (FIG. 15C). In light of the manydisclosed examples of laser cutting to achieve a desired shape, one ofskill in the art will appreciate that numerous other shapes may also beachieved.

Any suitable laser may be used for laser cutting the PCD tables and/orPDCs. For example, solid state lasers, gas lasers, or chemical lasersmay be employed. One particularly suitable laser is a ytterbium fiberlaser. Other suitable lasers may include Nd:YAG lasers, CO₂ lasers, andcopper vapor lasers. In an embodiment, the power of the laser may bebetween about 1 watt and about 1000 watts, about 1 watt to about 500watts, or about 1 watt to about 100 watts. In another embodiment, laserpower may be between about 5 watts and about 50 watts. In anotherembodiment, laser power may be between about 10 watts and about 30 watts(e.g., about 20 watts).

IV. Rotary Drill Bits and Other Structures Including PDCs

The PDCs formed according to the various embodiments disclosed hereinmay be used as PDC cutting elements on a rotary drill bit. For example,in a method according to an embodiment of the invention, one or morePDCs may be received that were fabricated according to any of thedisclosed manufacturing methods and attached to a bit body of a rotarydrill bit.

FIG. 16 is an isometric view and FIG. 17 is a top elevation view of anembodiment of a rotary drill bit 300 that includes at least one PDCconfigured and/or fabricated according to any of the disclosed PDCembodiments. The rotary drill bit 300 comprises a bit body 302 thatincludes radially and longitudinally extending blades 304 having leadingfaces 306, and a threaded pin connection 308 for connecting the bit body302 to a drilling string. The bit body 302 defines a leading endstructure for drilling into a subterranean formation by rotation about alongitudinal axis 310 and application of weight-on-bit. At least onePDC, configured according to any of the previously described PDCembodiments, may be affixed to the bit body 302. With reference to FIG.17, each of a plurality of PDCs 312 is secured to the blades 304 of thebit body 302 (FIG. 16). For example, each PDC 312 may include a PCDtable 314 bonded to a substrate 316. More generally, the PDCs 312 maycomprise any PDC disclosed herein, without limitation.

In addition, if desired, in some embodiments, a number of the PDCs 312may be conventional in construction. Also, circumferentially adjacentblades 304 define so-called junk slots 320 therebetween. Additionally,the rotary drill bit 300 includes a plurality of nozzle cavities 318 forcommunicating drilling fluid from the interior of the rotary drill bit300 to the PDCs 312.

FIGS. 16 and 17 merely depict one embodiment of a rotary drill bit thatemploys at least one PDC fabricated and structured in accordance withthe disclosed embodiments, without limitation. The rotary drill bit 300is used to represent any number of earth-boring tools or drilling tools,including, for example, core bits, roller-cone bits, fixed-cutter bits,eccentric bits, bi-center bits, reamers, reamer wings, or any otherdownhole tool including superabrasive compacts, without limitation.

The PDCs disclosed herein (e.g., PDC 100 of FIG. 1A) may also beutilized in applications other than cutting technology. For example, thedisclosed PDC embodiments may be used in wire dies, bearings, artificialjoints, inserts, cutting elements, heat sinks, jewelry, and tooling suchas shaped dies and shaped punches. PDCs including non-planar surfaces(e.g., exterior surface 106) may be particularly useful in applicationssuch as jewelry and tooling. Thus, any of the PDCs disclosed herein maybe employed in an article of manufacture including at least one PCDtable or compact.

Thus, the embodiments of PDCs disclosed herein may be used in anyapparatus or structure in which at least one conventional PDC istypically used. In an embodiment, a rotor and a stator, assembled toform a thrust-bearing apparatus, may each include one or more PDCs(e.g., PDC 100 of FIG. 1A) configured according to any of theembodiments disclosed herein and may be operably assembled to a downholedrilling assembly. U.S. Pat. Nos. 4,410,054; 4,560,014; 5,364,192;5,368,398; 5,480,233; 7,552,782; and 7,559,695, the disclosure of eachof which is incorporated herein, in its entirety, by this reference,disclose subterranean drilling systems within which bearing apparatusesutilizing superabrasive compacts disclosed herein may be incorporated.The embodiments of PDCs disclosed herein may also form all or part ofheat sinks, wire dies, bearing elements, cutting elements, cuttinginserts (e.g., on a roller-cone-type drill bit), machining inserts, orany other article of manufacture as known in the art. Other examples ofarticles of manufacture that may use any of the PDCs disclosed hereinare disclosed in U.S. Pat. Nos. 4,811,801; 4,268,276; 4,468,138;4,738,322; 4,913,247; 5,016,718; 5,092,687; 5,120,327; 5,135,061;5,154,245; 5,460,233; 5,544,713; and 6,793,681, the disclosure of eachof which is incorporated herein, in its entirety, by this reference.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments are contemplated. The various aspects andembodiments disclosed herein are for purposes of illustration and arenot intended to be limiting. Additionally, the words “including,”“having,” and variants thereof (e.g., “includes” and “has”) as usedherein, including the claims, shall be open ended and have the samemeaning as the word “comprising” and variants thereof (e.g., “comprise”and “comprises”).

What is claimed is:
 1. A method of forming a polycrystalline diamondcompact having a selected geometry, the method comprising providing aprecursor polycrystalline diamond compact including a polycrystallinediamond table attached to a substrate, the polycrystalline diamond tableformed at a sintering pressure of at least about 7.5 GPa, thepolycrystalline diamond table including an upper surface and a lateralsurface; applying laser energy to a portion of the upper surface of thepolycrystalline diamond table to remove diamond material therefrom toform at least one groove offset inwardly and spaced from the lateralsurface by a portion of the polycrystalline diamond table; and removingat least a portion of the substrate extending laterally beyond the atleast one groove of the polycrystalline diamond table to form thepolycrystalline diamond compact having the selected geometry.
 2. Themethod of claim 1, wherein the at least one groove includes at least oneannular groove in top plan view.
 3. The method of claim 1, whereinremoving at least a portion of the substrate extending laterally beyondthe at least one groove includes removing the at least a portion of thesubstrate by grinding, lapping, electrical-discharge machining, orcombinations thereof.
 4. The method of claim 1, wherein thepolycrystalline diamond table includes a generally cylindricalpolycrystalline diamond and the substrate includes a generallycylindrical substrate.
 5. The method of claim 1, wherein thepolycrystalline diamond table is at least partially leached.
 6. Themethod of claim 1, wherein the polycrystalline diamond table isunleached.
 7. The method of claim 1, wherein the polycrystalline diamondtable exhibits a G_(ratio) of about 8.0×10⁶ to about 15.0×10⁶.
 8. Themethod of claim 1, wherein the portion of the upper surface of thepolycrystalline diamond table is removed to a first depth as a result ofa first pass of the laser energy, and a remainder of the portion of theupper surface of the polycrystalline diamond table adjacent to anddeeper than the portion removed in the first pass is removed as a resultof at least one subsequent pass of the laser energy so that the portionis progressively removed through multiple subsequent passes of the laserenergy, and wherein a depth of diamond material removed during each passof the laser energy is sufficiently low so as to prevent substantialthermal damage to the polycrystalline diamond table.
 9. The method ofclaim 8, wherein each of the subsequent passes of the laser energyremoves a depth of about 0.003 inch to about 0.05 inch of diamondmaterial as the portion of the upper surface of the polycrystallinediamond table is progressively ablated.
 10. The method of claim 1,wherein the at least one groove terminates at a vertex.
 11. The methodof claim 1 wherein applying laser energy to a portion of the uppersurface of the polycrystalline diamond table to remove diamond materialtherefrom to form at least one groove includes forming the at least onegroove wide enough to accommodate an electrical-discharge machiningwire.
 12. The method of claim 1, further comprising, after applying thelaser energy to the portion of the upper surface of the polycrystallinediamond table, removing at least a portion of the substrate by wireelectrical-discharge machining.
 13. A method of forming apolycrystalline diamond compact having a selected geometry, the methodcomprising providing a precursor polycrystalline diamond compactincluding a polycrystalline diamond table attached to a substrate, thepolycrystalline diamond table including a plurality of bonded diamondgrains defining a plurality of interstitial regions therebetween, thepolycrystalline diamond table further including an upper surface and alateral surface, the polycrystalline diamond table further including: anunleached region adjacent to and extending from the substrate towardsthe upper surface, the unleached region including at least one of acatalyst or an infiltrant disposed in at least a portion of theinterstitial regions thereof; and an at least partially leached regionextending from the upper surface to the unleached region, the at leastpartially leached region having at least one of the catalyst or theinfiltrant at least partially removed from at least a portion of theinterstitial regions thereof; applying laser energy to a portion of theupper surface of the polycrystalline diamond table to remove diamondmaterial therefrom to form at least one groove offset inwardly andspaced from the lateral surface by a portion of the polycrystallinediamond table; and removing at least a portion of the substrateextending laterally beyond the at least one groove of thepolycrystalline diamond table to form the polycrystalline diamondcompact having the selected geometry.
 14. The method of claim 13,wherein applying laser energy to a portion of the upper surface of thepolycrystalline diamond table to remove diamond material therefrom toform at least one groove includes forming the at least one groovethrough at least the at least partially leached region.
 15. The methodof claim 13, wherein the at least partially leached region includessubstantially no catalyst or substantially no infiltrant therein. 16.The method of claim 13, wherein the polycrystalline diamond tableexhibits a G_(ratio) of at least about 4.0×10⁶.
 17. The method of claim13, further comprising, after applying laser energy to a portion of theupper surface of the polycrystalline diamond table, removing portions ofthe polycrystalline diamond table underlying the at least one groove byelectrical-discharge machining.
 18. A method of forming apolycrystalline diamond compact having a selected geometry, the methodcomprising providing a precursor polycrystalline diamond compactincluding a polycrystalline diamond table attached to a substrate, thepolycrystalline diamond table including a plurality of bonded diamondgrains, the polycrystalline diamond table further including an uppersurface and a lateral surface; applying laser energy to a portion of theupper surface of the polycrystalline diamond table to remove diamondmaterial from at least one region of the polycrystalline diamond table,wherein the portion of the upper surface of the polycrystalline diamondtable is removed to a first depth as a result of a first pass of thelaser energy, and a remainder of the portion of the upper surface of thepolycrystalline diamond table adjacent to and deeper than the portionremoved in the first pass is removed as a result of at least onesubsequent pass of the laser energy so that the portion is progressivelyremoved through multiple subsequent passes of the laser energy; whereina depth of diamond material removed during each pass of the laser energyis sufficiently low so as to prevent substantial thermal damage to thepolycrystalline diamond table; and subsequent to applying laser energy,removing at least a portion of the substrate underlying the at least oneregion.
 19. The method of claim 18, wherein removing at least a portionof the substrate includes removing the at least a portion of thesubstrate underlying the at least one region by grinding, lapping,electrical-discharge machining, or combinations thereof.
 20. The methodof claim 18, wherein removing at least a portion of the substrateincludes removing the at least a portion of the substrate underlying theat least one region by grinding.
 21. The method of claim 18, wherein theat least one region of the polycrystalline diamond table includes atleast one peripheral portion of the polycrystalline diamond table. 22.The method of claim 18, wherein the polycrystalline diamond tableincluding the at least one region thereof removed therefrom defines atleast one groove offset inwardly from the lateral surface of thepolycrystalline diamond table.
 23. The method of claim 18 wherein theselected geometry is non-cylindrical.
 24. The method of claim 18,wherein the polycrystalline diamond table includes: an unleached regionadjacent to and extending from the substrate towards the upper surface,the unleached region including at least one of a catalyst or aninfiltrant disposed in at least a portion of the interstitial regionsthereof; and an at least partially leached region extending from theupper surface to the unleached region, the at least partially leachedregion having at least one of the catalyst or the infiltrant at leastpartially removed from at least a portion of the interstitial regionsthereof.
 25. The method of claim 24, wherein applying laser energy to aportion of the upper surface of the polycrystalline diamond table toremove diamond material from at least one region of the polycrystallinediamond table includes removing the diamond material from at least theat least partially leached region of the polycrystalline diamond table.